Methods are available from prior art for the fabrication of lenses and mirrors based on diffractive waveplates. However, some applications require that the diffractive waveplate lenses and mirrors be larger in size, have shorter focal length, and have more closely spaced grating lines than is achievable based on prior art techniques. Also, with presently-available fabrication techniques, imperfections in the fabricated parts prevent their use in certain applications that require close tolerances. Therefore there is a need for methods of fabrication of diffractive waveplate lenses and mirrors with larger size, shorter focal length, finer grating spacing, and more exact correspondence between the design and the fabricated parts than is achievable with said prior art.
The lenses and mirrors that are used as examples in the present disclosure have circular symmetry, but the methods disclosed herein are applicable to other device structures. The techniques disclosed herein for achieving diffractive waveplate devices with finer grating patterns than are achievable using prior art (i.e. grating patterns with grating lines more closely spaced than are achievable with prior art) are applicable to many other geometrical arrangements as well. For example, these techniques could also be applied to lenses or mirrors in which the optical axis orientation pattern, instead of having circular symmetry, has cylindrical symmetry.
Thus, the need exists for solutions to the above problems with the prior art.